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Preface

So, how much electronics do you need to know to be able to create something
interesting, or creatively modify something that already exists? Well, that
depends on where you start in the creative process. It also depends on your
willingness to seek out new knowledge and acquire new skills as you go along.

The primary purpose of this book is to give you a reference for some of
the more arcane (and possibly mundane) but essential aspects of
electronics. These include things you would typically learn
on the job and from years of experience, such as how to read the datasheet for an electronic component, determining how many things can be
connected to an interface pin on a microcontroller, how to assemble
various types of connectors, how to minimize noise and interference
on a signal interface circuit, how to determine the resolution of an
analog-to-digital converter, how various types of serial and network
interfaces work, and how to use open source tools for schematic capture
and PCB layout. And, of course, we will also cover
the tools used in electronics work and how they are used, and we’ll
examine what’s available in terms of test equipment beyond the
garden-variety digital multimeter.

We’ll start off with an introduction to the underlying physics of
electricity that dispenses with the water-flowing-in-a-pipe analogy and
gets right to the heart of the matter with a look at how atoms pass
electrons around. We’ll then examine the basic concepts of voltage and
current. For those readers who might need or want a more detailed
discussion of basic electrical theory, it can be found in Appendix A.

I should point out that this book is not intended to be an in-depth tutorial
on electronics theory. There are already many excellent books on that topic,
and to repeat that here would just be a pointless exercise in killing trees.
So, while there is some introductory material to set the stage, so to speak,
the primary intent of this book is to provide you with a reference for topics
that aren’t usually covered in an electronics text or a step-by-step project
book.

With this book, perhaps one or two of the suggested reference works in
Appendix C, and your own enthusiasm and ambition, you should be able to
create that gadget or system you’ve been wanting to build and have it work
as you intended. And remember, it’s not the end of the world if you
accidentally convert an electronic component into charcoal. It happens all
the time; it’s called learning.

Who This Book Is For

This book is for anyone with a desire to build an electronic device of some sort, but,
to the maximum extent possible, I have made no assumptions about your skill level. What I have assumed is that you might not be familiar with the hardware,
components, tools, and techniques that are used in electronics, or perhaps you
already know something about electronics but could use some help with some of the more
arcane aspects of the craft.

With this book as a workbench reference and guide to more detailed sources of information,
you should be able to get started on building a nifty gadget and avoid some (hopefully,
most) of the pitfalls that await the unwary. I’ve made the assumption that you will
follow the pointers given to learn more about the various topics this book covers, and it
covers a lot. It’s simply not possible to cover all the topics presented in this book at
more than just a surface level; the resulting tome would be huge. In lieu of a lot
of details, I’ve tried to provide enough information to give you a basic understanding
of the topics and a foundation to build upon.

So, if you’ve been thinking about something you’d like to build but aren’t sure how to
go about it, or you already know a fair amount about electronics but perhaps
need some help putting it all together, then this book is for you.

How This Book Is Organized

Each chapter is devoted to a specific topic, ranging from hardware (screws,
nuts, and bolts) to tools, and from switches, relays, and passive components
to active solid-state parts. Each chapter is designed to allow you
to easily find a specific subject and get quick answers to your questions:

Often overlooked or taken for granted, fasteners and fastening methods
are essential to a successful project. The choice of fasteners can
also have a major effect on the aesthetics of a project, so getting the
right parts for the job can make the difference between elegant and
clunky.

This chapter describes the basic tools needed to work with electronics (diagonal
cutters, flush cutters, pliers, screwdrivers, etc.), along with some tools
not commonly discussed in other texts, including things like crimp
tools, rotary tools, step drills, professional grade soldering
stations, and magnifiers and microscopes for surface-mount work.

Short sections for each tool discuss its uses and applications, including
the correct use of sockets, wrenches, and screwdrivers; how to solder various
component types, including surface-mounted components; and how
to correctly size the holes needed to mount components like switches, lamps,
or printed circuit boards in a chassis or panel.

An overview of power supplies for both DC and AC
current, ranging from batteries to Variac-type devices, this chapter gives
special attention to inexpensive DC power supplies in the form of plug-in
modules (so-called wall warts). It also presents a discussion of fuses
and circuit breakers and offers guidance on how to select an appropriate rating
for these essential protection devices.

This chapter is a survey of the types of switches available and where they
are typically used. This covers conventional switches, such as toggles and
panel-mount pushbuttons, along with other types, such as PCB-mounted pushbuttons
and membrane-type switches.

In electronics, almost everything connects to something, somewhere. This chapter
describes the various types of connectors available, where they are commonly
used, and how to assemble some of the more common types, such as DB-9, DB-25,
high-density terminal blocks, and the 0.1-inch grid pin connectors found on
Arduino, Raspberry Pi, and BeagleBone boards. It also covers related topics,
such as soldering, crimping, and insulation displacement (IDC) techniques for
connector assembly. This chapter deals mostly with those connectors that a
typical human being can easily assemble without resorting to a microscope and
tweezers, or a special tool that costs hundreds of dollars.

Passive components are the framework on which circuits are built. This
chapter describes commonly encountered passive components such as resistors,
capacitors, and inductors, including both through-hole and surface-mounted
types. It also describes how to read component markings and how to understand
component ratings for power, temperature, and tolerance.

This chapter covers various types of active components, from diodes to ICs,
with photos and package outline drawings to illustrate the various types. It also discusses key points to bear
in mind when working with active components, such as static sensitivity, heat
damage from soldering, and some of the package types available for surface-mount
components.

Relays might be an old technology, but they are still essential in electronics.
This chapter covers the various types of relays available and their typical
applications. It describes types ranging from low-current, TTL-compatible
reed relays to high-power types used to control AC current. It also covers
techniques for controlling a relay from a low-voltage circuit.

Along with a condensed description of basic logic components (OR, NOR, AND, NAND, etc.),
logic families (TTL, CMOS), and some examples of combinatorial logic circuits, this chapter
also presents an introduction to microprocessors and microcontrollers, in terms
of what is currently available and what you might need or encounter in your
own activities.

This chapter covers the basics of using a discrete signal (a single logic I/O
port) to control things in the physical world. It also includes a discussion on the
use of buffers, using both individual transistors and ICs, along with
a discussion of current sink and sourcing considerations.

This chapter describes the basics of analog interfaces, both input and output,
and includes discussions on resolution, speed, and the effects of quantization.
It also covers aspects of analog I/O, such as voltage range, buffering, and circuit
design considerations to reduce noise and improve performance.

Topics include common interfaces, from board-level SPI and I2C to RS-232, RS-485,
USB, and Ethernet. This chapter also covers wireless interfaces, such as generic 2.45 GHz
devices, 802.11 wireless networking, ZigBee, and Bluetooth. Serial and parallel, the two
primary interface families, are introduced, followed by a discussion of synchronous and
asynchronous modes of operation. The remainder of the chapter is organized into sections
that cover each topic with a high-level technical discussion, and representative component
part numbers are provided where applicable.

This chapter is an overview of PCB design and layout, with a focus on technique rather than specific
tools. The chapter starts off with an introduction to PCB technology and concepts, including
circuit board substrate materials and circuit trace (or track, if you will) pattern etching
and plating techniques. An example from a real project is used to demonstrate the basic steps
involved in creating a double-sided PCB layout. The chapter wraps up with a collection of
general guidelines and tips.

A guide to the various options available for physically housing electronics, this chapter
includes a discussion of plastic versus metal, sources for chassis components, and the use
of unconventional enclosures to create unique packaging prototypes. Examples are given for
commercial off-the-shelf packages in the form of small plastic enclosures, metal enclosures
using both aluminum and steel sheet metal, extruded aluminum packages, and heavy-gauge kits
for more demanding applications.

A short tour of inexpensive test equipment, this chapter starts with the ubiquitous digital
multimeter and moves on to oscilloscopes, signal generators, and logic analyzers. The examples include readily available, low-cost devices such as single- and dual-channel pocket digital
oscilloscopes from China, and a multi-waveform signal generator module for the Arduino. The
intent is to give you some suggestions that don’t involve breaking the bank to purchase
high-end test equipment (not that there’s anything wrong with high-end gear—it’s generally
excellent; it just happens to be rather expensive).

For anyone interested, or anyone who could benefit from it for their projects,
this appendix presents a terse, high-level overview of basic electronics theory
beyond what Chapter 1 provides. Topics covered include capacitance, series and
parallel resistor and capacitor circuits, basic AC circuit theory, inductance,
noise, impedance, and grounding techniques.

This appendix defines the basics of schematic drawings, with examples of commonly
encountered symbols. Light on text but heavy on graphics, this appendix
is intended to be a place where you can quickly find the definition for a particular
symbol. It also describes some available open source tools for
creating schematic diagrams.

This appendix includes URLs for electronics distributors, sources for mechanical
components, and vendors of surplus components of various types, as well as a brief discussion of buying electronics components and other
items from vendors on eBay, with some guidance and caveats.

This appendix lists most all of the IC components and modules mentioned in this book.
While this collection is by no means comprehensive, it does contain enough representative
parts from each category to provide a solid starting point for a new design.

Endorsements

There aren’t any endorsements in this book, at least not intentionally. I’ve made reference
to many different component manufacturers, suppliers, and authors, but I’ve tried to
be evenhanded about it. Any trademarks mentioned are the property of their respective owners
and appear here solely for reference. As for the photography, I tried to use my own tools
and other items as much as possible, and although an image may show a particular brand or
model, that doesn’t mean it’s the only type available. It just happens to be the one that
I own and use in my own shop. In some cases, I’ve used images with permission or from sources
such as the Library of Congress, and this is noted as appropriate.

Acknowledgments

This book would not have been possible without the enduring patience and support of my
family. In particular, I would like to acknowledge the photography and organizational
assistance of my daughter, Seren, who put up with my fussiness and took yet another
picture of something or other in the light tent for me when I didn’t like the pose or
lighting of the first (or second, or third) attempt. And, of course, my lovely wife, Carol,
who would bring me things to eat in my shop and fret about me losing sleep.

Special thanks to Mike Westerfield for his technical review and input. It’s always good to
have more than one pair of eyes on the details, and Mike pointed out some rough spots that
needed some editing and clarification. The end result is a better book, and it just goes
to show why review is a crucial part of any development process.

The feedback from readers of the early release has been invaluable. Special thanks to those
who suggested additions for the bibliography in Appendix D (you know who you are) and for
the many helpful comments and constructive criticisms.

I would also like to thank the editorial staff at O’Reilly for the opportunity to work
with them once again, especially Brian Sawyer for his willingness to put up with me in
general, Mike Loukides for giving me this opportunity to write another book for O’Reilly,
and the Atlas team for responding to my technical issues in a timely and helpful manner.

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